Use t.Fatal instead of t.Error

[sagikazarmark]

Is your feature request related to a problem? Please describe.
Consider the following example:

func check(t gobdd.StepTest, ctx gobdd.Context, sum int) {
	received, err := ctx.GetInt("sumRes")
	if err != nil {
		t.Error(err)

		return
	}

	if sum != received {
		t.Error(errors.New("the math does not work for you"))
	}
}

Because t.Error does not cause the test to fail immediately, we need to return manually from the function.

Describe the solution you'd like
By using t.Fatal the test fails immediately, making the code more concise.

Describe alternatives you've considered
One could even use testify (assert and require).

Additional context
This is true for some of the internal code of gobdd.